Prosthetic implants, periprosthetic and osteoarticular tissues are specimens of choice for diagnosis of bone and joint infections including prosthetic joint infections (PJIs). However, it is widely known that cultures from prostheses and tissues may fail to yield microbial growth in up to one third of patients. In the recent past, treatment of prosthetic implants have been optimized in order to improve sensitivity of microbiological cultures, while less attention has been addressed to tissue samples. For these latter homogenization is considered the best procedure, but it is quite laborious, time-consuming and it is not always performed in all laboratories. Dithiothreitol (DTT) has been proposed as an alternative treatment to sonication for microbiological diagnosis of PJIs. In this study, we evaluated the applicability of MicroDTTect treatment, a closed system developed for transport and treatment of tissues and prosthetic implants with DTT.
For evaluation of applicability of MicroDTTect to tissue specimens, samples (tissues and, in case of PJI, prosthetic implants) from 40 patients (12 PJIs and 5 osteomyelitis and 23 not-infected) were evaluated. MicroDTTect system consists of a sterile plastic bag containing a reservoir which allows for release of a 0.1% (v:v) DTT solution, once the sample is placed into the bag. Comparison of MicroDTTect treatment of prostheses with sonication included samples from 30 patients (14 with aseptic loosening of the prosthesis and 16 with PJIs). Of two tissue samples from the same region, one was placed into MicroDTTect bag and the other was collected in a sterile container with addition of sterile saline. After agitation and centrifugation of the eluate, aliquots of the pellets were plated on agar plates and inoculated into broths which were incubated for 48 hrs and 15 days, respectively.
Treatment of prosthetic implants with MicroDTTect showed a higher specificity and sensitivity than sonication (specificity 92.8% vs 85.7%; sensitivity: 87.5% vs 75.0 % DTT vs sonication). When used for tissue treatment, MicroDTTect showed a sensitivity of 82.3% and a specificity of 97% which were higher than that observed when saline was used (sensitivity: 64.7%; specificity 91%).
Treatment of tissues and prosthetic implants with MicroDTTect may be a practicable strategy to improve microbiological diagnosis of osteoarticular infections, reducing sample manipulation and therefore limiting sample contamination. Moreover, use of MicroDTTect does not require dedicated instrumentation, and is time and cost saving.